MUTATIONS 121 



the brightest heads of the most beautiful double commercial 

 varieties of composites." He adds : 



The race has at once become permanent and constant. Real atavists or 

 real reversionists were seen no more after the first purification of the race. 

 It has of course a wide range of fluctuating variability (considering all 

 the heads), but the lower limit has been worked up to about thirty-four 

 rays, a figure never reached by the grandiflorum parent, from which my 

 new variety is sharply separated. 



Unfortunately, the best heads now produced are sterile, so 

 that seeds must be secured from inferior stock and the variety 

 must be propagated from slightly inferior parentage. Selection 

 has, therefore, reached its limit, unless a fertile strain arises, 

 which is entirely possible. 



This mutation is decidedly new. It had never been known, 

 nor had anything approaching it ever been discovered in this 

 species. The only hope that it might appear was belief in the 

 principle, and the fact that doubling had taken place in other 

 composite. Right royally was De Vries's prophecy fulfilled, and 

 again was he "present" when it happened; not only that, but 

 in this case nature evidently would not have produced this 

 mutation without assistance. Here nature has accomplished 

 with help a work which she was powerless to accomplish alone, 

 but abundantly able to achieve with a little assistance. 



Experiments in the production of new species. 1 De Vries was 

 not content with the simple production of varieties. He desired 

 to show that the principle of mutation produces species as well. 2 

 He cultivated many species of wild plants in his garden, choos- 

 ing wild in preference to cultivated, because he regarded the 

 latter as evidence of what had recently taken place and, there- 

 fore, not the best stock for further mutation in the near future. 

 In other words, he desired to be present before the mutation 



1 De Vries, Species and Varieties, etc., pp. 516-546. 



2 He distinguishes sharply between varieties and species. The variety differs 

 from the main stock in but a single character, progressive or retrogressive, while 

 the species differs in all characters, some of which are perhaps progressive and 

 others retrogressive. He likes to distinguish elementary species from all other 

 types, as these are in his estimation the most stable forms in nature ; and when 

 any race assumes the " mutative state " it is likely to throw off, if conditions are 

 favorable, a large number of new elementary species, each with its new center of 

 variability. 



